Re: Opinion poll: for loop vs while loop with Iterators.
bjeremy wrote:
Daniel Pitts wrote:
Java 1.5 finaly gave us an elegant for each construct, but for-each
lacks the ability to manipulate the underlying Iterable structure.
Generally, the way to do this is (in pseudo-code:)
Obtain the iterator.
L: Check if it has a next element
get the next element
process the element.
repeat from L
This can be coded in Java a few ways.
// For method:
for (Iterator<E> iterator = iterable.iterator(); iterator.hasNext(); )
{
E e = iterator.next();
if (shouldRemove(e)) {
iterator.remove(e);
}
}
// vs
// While method:
Iterator<E> iterator = iterable.iterator();
while (iterator.hasNext()) {
E e = iterator.next();
if (shouldRemove(e)) {
iterator.remove(e);
}
}
Both approaches have their pros and cons, but I'm interested to see
what people think.
I'll post my opinion later.
In "Effective Java" by Josh Bloch (p. 142 for all those who wish to
check this), Josh argues that we should prefer using for loops as
opposed to while loops. His reasoning is that the loop structure allows
us an opportunity to limit the scope of variables. The for loop enables
us to declare loop variables and thus limit their scope to the exact
region needed. His caveat is if you happen to need the variable after
the execution of the loop, you probably don't want to make it a loop
variable.
My personal preference is the while loop.
I agree that limiting the scope of temporary variables is useful,
however, there are clearer ways to accomplish this. My personal
favorite is to introduce a method that does the work of the loop. That
has the added benefit of explaining what the loop does, by giving it a
name.
Alternatively, to limit the scope other ways you can do stuff like:
public static void main(String...args) {
{
final int myInt = 0;
System.out.println(myInt);
}
{
final int myInt = 2;
System.out.println(myInt);
}
}